Handheld cutter and method for cutting vinyl floor coverings

BACKGROUND

p-00021. Field of the Invention

p-0003The present invention relates to handheld tools, and more specifically, to a handheld cutter for vinyl floor coverings.

p-00042. Description of Related Art

p-0005The use of vinyl floor covering materials is quite common in the construction of both homes and commercial buildings. Vinyl floor covering materials are durable, come in a wide variety of colors and textures, and can be relatively inexpensive. A skilled craftsman experienced in the installation of vinyl floor coverings can generally install the material on the floors of several rooms in a matter of hours. However, inexperienced construction workers, or homeowners attempting the installation themselves, often run into difficulties. It can be difficult to get the vinyl floor covering materials to fit neatly in corners and tight spaces. It can also be difficult to make a straight cut so the vinyl floor covering lies a uniform distance from the wall. Quite often the inexperienced installer will end up with unsightly installation flaws, and will sometimes waste material in repeated attempts to get an acceptable fit.

p-0006What is needed is an improved way of cutting and installing vinyl floor coverings.

SUMMARY

p-0007This disclosure addresses the above stated needs by providing various embodiments of vinyl cutting tools and methods of using the tools for cutting vinyl floor coverings. Various embodiments are drawn to a cutting tool for cutting flexible flooring material. The tool has a tool body with a bottom surface that slides across the flooring material as it is being cut. The tool body also has a blade holding portion that is shaped to receive a hook blade inserted into it, and hold the hook blade for cutting the flexible flooring material. The blade holding mechanism removably affixes the hook blade to the blade holding portion in an orientation parallel to a surface of the blade holding portion, and closer to the trailing edge than the leading edge of the tool. In accordance with various embodiments the blade holding mechanism holds the bottom most part of the hook blade (e.g., the hook blade tip) above the level of the bottom surface of the tool. The excess vinyl is curled up against the wall, and the cutting tool's hook blade cuts the vinyl at a point near the wall where it curls up. The cutting edge of the hook blade faces the leading edge of the tool body relative to a direction of cutting.

p-0008In some embodiments the orientation of the hook blade is reversible in order to change the cutting direction. In other embodiments there are two hook blades, and a different hook blade is used for cutting in either direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate various embodiments of the invention. Together with the general description, the drawings serve to explain the principles of the invention. In the drawings:

<figref idrefs="DRAWINGS">FIG. 1A</figref> depicts an oblique view of the hand-hold side of one embodiment of the tool from a top perspective;

<figref idrefs="DRAWINGS">FIG. 1B</figref> depicts an oblique view of the cutting blade side of the tool from a top perspective;

<figref idrefs="DRAWINGS">FIG. 2A</figref> depicts a side view of one embodiment of the tool;

<figref idrefs="DRAWINGS">FIG. 2B</figref> depicts a front view of the blade holding face of the tool with the blade installed to make a left cut as viewed from behind the tool;

<figref idrefs="DRAWINGS">FIG. 2C</figref> depicts a front view of the blade holding face of the tool with the blade installed to make a right cut;

<figref idrefs="DRAWINGS">FIG. 3A</figref> depicts a top view of one embodiment of the tool;

<figref idrefs="DRAWINGS">FIG. 3B</figref> depicts a bottom view of one embodiment of the tool;

<figref idrefs="DRAWINGS">FIGS. 4A-B</figref> depict oblique views of an embodiment of the cutting tool that has two blades; and

<figref idrefs="DRAWINGS">FIG. 4C</figref> depicts a side view of a two blade embodiment of the cutting tool.

DETAILED DESCRIPTION

p-0019<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> depict oblique views of a vinyl cutting tool according to one embodiment. <figref idrefs="DRAWINGS">FIG. 1A</figref> depicts an oblique view of the hand-hold side of one embodiment of the tool from a top perspective. <figref idrefs="DRAWINGS">FIG. 1B</figref> depicts another oblique view of the cutting blade side of the same embodiment of the tool, also from a top perspective. In the view of <figref idrefs="DRAWINGS">FIG. 1B</figref>, the tool is rotated approximately 135 degrees counter clockwise as compared to the view of <figref idrefs="DRAWINGS">FIG. 1A</figref>. The vinyl cutting tool shown in <figref idrefs="DRAWINGS">FIG. 1B</figref> is intended to cut in the direction of arrow <b>101</b>, with the hook blade <b>105</b> nearer to the trailing edge than to the leading edge of the tool relative to the cutting motion. The phrase nearer to the trailing edge than to the leading edge means that the hook blade <b>105</b> is behind the centerline <b>113</b> of the tool relative to the cutting direction <b>101</b>. In other words the cutting edge <b>111</b> of hook blade <b>105</b> faces toward the cutting direction <b>101</b> and the tip of hook blade <b>105</b> is typically behind the centerline <b>113</b> of the tool (towards the trailing edge). The extent that hook blade <b>105</b> is positioned toward the trailing edge as compared to the leading edge of the tool can vary, depending upon the specifics of the implementation. The orientation toward the trailing edge can be measured by the position of the hook blade tip in relation to the leading and trailing edges of the tool (e.g., the corners of the tool closest to the wall ahead of and behind the hook blade). In the embodiment depicted in <figref idrefs="DRAWINGS">FIG. 1B</figref> hook blade <b>105</b> (as measured by the tip position) is approximately 75% of the way towards the trailing edge as compared to the leading edge. In some embodiments the tip of hook blade <b>105</b> may hang out past the trailing edge while in other embodiments the tip of hook blade <b>105</b> may be positioned as far forward as the centerline <b>113</b>, or at any position or range of positions between these two points. Some implementations may even have the hook blade positioned ahead of the centerline <b>113</b>, although the stability of the tool tends to be better if the blade is positioned at the centerline or further back relative to the cutting direction.

p-0020Various embodiments use a hook blade <b>105</b> which is a cutting blade with a concave cutting edge. Most embodiments of the hook blade have a sharp tip at the end. Various embodiments use a hook blade with a sharpened cutting edge around an arc at least 90 along an interior curve of the blade. The hook blade depicted in <figref idrefs="DRAWINGS">FIG. 1B</figref> is a model 11-961 hook blade from the Stanley Tool Company™. The model 11-961 is typical of the type of hook blade that may be used, although different hook blades may be used in various embodiments. The hook blade may be made from various materials, including steel, stainless steel, or any of a number of alloys known to those of skill in the cutting instrument art that would be sufficient for cutting vinyl flooring.

p-0021In <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>, so long as the hook blade <b>105</b> is affixed in the same position in both views, the cutting motion will be the same relative to both tools. That is, cutting direction <b>101</b> relative to the tool shown in <figref idrefs="DRAWINGS">FIG. 1A</figref> is the same direction relative to the tool as cutting direction <b>101</b> shown for the tool shown in <figref idrefs="DRAWINGS">FIG. 1B</figref>. However, in various embodiments the hook blade <b>105</b> can be moved to the opposite side of the tool to cut in the other direction. The hook blade <b>105</b> is removably affixed to a blade holding face <b>121</b> of the tool. The term “removably affixed” means that the hook blade <b>105</b> can be affixed to the tool for cutting, and then be removed from the tool, either for replacement, to flip the blade over (to a sharper cutting edge) for cutting in the same direction, or to change the orientation of the blade to reverse the cutting direction. The embodiment of <figref idrefs="DRAWINGS">FIG. 1B</figref> depicts a recessed (or depressed) blade holding portion <b>119</b> of the blade holding face <b>121</b> shaped to receive a hook blade <b>105</b>—that is, to have a hook blade <b>105</b> inserted into the recessed blade holding portion <b>119</b>. <figref idrefs="DRAWINGS">FIG. 1B</figref> depicts the upper end of the cutting blade resting against an upper edge <b>115</b> of the recessed blade holding portion <b>119</b>.

p-0022The cutting direction may be reversed in <figref idrefs="DRAWINGS">FIG. 1B</figref> by removing the hook blade <b>105</b>, and flipping it over laterally so that its upper edge rests against upper edge <b>117</b> of the blade holding portion. When the blade is reversed in this manner the hook end of hook blade <b>105</b> will be nearest the point <b>123</b> of blade holding portion <b>119</b>, and the cutting direction will then be the direction of dashed line <b>103</b>. In the embodiment depicted in <figref idrefs="DRAWINGS">FIG. 1B</figref> the recessed blade holding portion <b>119</b> provides a close fit to hold hook blade <b>105</b> thinly in place with little or no movement of hook blade <b>105</b> on the tool during the cutting operation. The tolerances of the tool are such that hook blade <b>105</b> fits snugly within recessed blade holding portion <b>119</b>. In the embodiment shown in the figures the hook blade <b>105</b> is held in place with magnet <b>127</b>. Other implementations use various other blade holding means, including for example, a threaded bolt, a latch mechanism, a sliding gate mechanism, a hole into which the blade can be inserted, or any other such holding mechanisms known to those skilled in the art. Aspects of the removal and reversal of the tool's cutting blade is also described in conjunction with <figref idrefs="DRAWINGS">FIGS. 2A-C</figref>.

p-0023The tool may be grasped in any manner that is comfortable for the user to firmly grip the tool as it is being moved in a cutting direction. For example, in the embodiments depicted in <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> with the cutting directions as shown with arrows <b>101</b> and <b>103</b>, a right handed user might grasp the tool body placing his (or her) right thumb at gripping portion <b>107</b> and one or more fingers on gripping portion <b>109</b>. This allows the tool to be held firmly to press the vinyl flat against the floor underneath the tool's body. The front edge (the end towards the blade) of the bottom portion of the vinyl cutting tool is beveled to provide a gap between the hook blade <b>105</b> and the bottom portion of the tool that rests firmly against the vinyl as it is being cut. This beveled edge cannot be seen in the views of <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> due to the angle looking from above. This beveled edge is shown in the cross-sectional view of the vinyl relative to the tool of <figref idrefs="DRAWINGS">FIG. 2A</figref>.

p-0024<figref idrefs="DRAWINGS">FIG. 2A</figref> depicts a side view of one embodiment of the cutting tool. In this view the cutting blade <b>205</b> can be seen slicing through a piece of vinyl <b>290</b> that is positioned on a floor near a wall <b>280</b> with the excess vinyl to be trimmed off curling up against the wall. When installing vinyl flooring it would be quite difficult to cut the vinyl to fit up against the walls before laying it down. Professional installers typically use a piece of vinyl flooring material that is somewhat larger than needed, and then trim the excess off near the wall so the material is right sized.

p-0025Various embodiments of the cutting tool feature a bevel face <b>225</b> adjacent the hook blade <b>205</b>. The bevel face <b>225</b> allows the vinyl to curl up from the floor against the wall <b>280</b> while the bottom surface <b>229</b> of the tool presses the vinyl firmly against the floor. The space in front of and beneath the bevel face <b>225</b> provides room for the bend of the vinyl, since vinyl flooring won't easily bend at a 90 degree angle without cracking or wrinkling. The bevel face <b>225</b> also raises the bottom edge of the blade holding face <b>221</b> up off the floor level, providing a space for the hook blade <b>205</b> to hang down without reaching the floor level or the level of the bottom surface <b>229</b> of the tool. In this way the tool's bottom surface <b>229</b> can be pressed against the vinyl <b>290</b>, holding it against the floor without dragging the hook blade <b>205</b> on the floor while the tool is being moved to cut the vinyl.

p-0026The bevel face <b>225</b> depicted in <figref idrefs="DRAWINGS">FIGS. 2A-2C</figref> is approximately ¾ inch in width, where the width is defined as the distance (measured behind centerline <b>213</b>) from the edge intersecting bottom surface <b>229</b> up to the edge of the bevel face intersecting the blade holding portion <b>219</b>. (The tool shown in <figref idrefs="DRAWINGS">FIGS. 2A-2C</figref> is approximately the actual size of one embodiment). The ¾ inch face width for the bevel face <b>225</b> is a typical value. However, in other embodiments the bevel face <b>225</b> can have a width as small as ⅛ inch to a width of 2 inches, or any range of widths or particular width value in between these two values. By cutting the vinyl <b>290</b> at a point part way up from the floor as the excess curls up against the wall, the cut vinyl will drop down very close to the edge of the wall, producing a straight cut which leaves the finished vinyl floor material the desired small gap away from the wall (e.g., often ⅛ inch to ⅜ inch, or other distance desired by the craftsman installing the vinyl). It is generally desirable to leave a small gap between the vinyl and the wall to avoid wrinkling in case the vinyl shifts or expands after it is laid.

p-0027In some embodiments the bottom surface <b>229</b> may be covered with a smooth material or durable fabric that aids in avoiding scratches to the surface of the vinyl <b>290</b> as it is being cut. Various implementations of the tool have bevel faces <b>225</b> at a number of different angles. The bevel angle <b>241</b> shown in <figref idrefs="DRAWINGS">FIG. 2A</figref> is approximately 35 degrees. While a bevel angle within the range of 20 to 50 degrees is typical, in various implementations the bevel angle may be as great as 80 degrees or as small as 10 degrees, or any value or range within these two values, so long as the bevel angle and width of the bevel face is sufficient to keep the tip of the hook blade <b>205</b> above the level of the tool's bottom surface <b>229</b>.

p-0028<figref idrefs="DRAWINGS">FIG. 2B</figref> depicts a front view of the cutting blade side of the tool with the blade installed to make a cut in direction <b>201</b>, a left moving cut as seen from the user's perspective behind the tool. <figref idrefs="DRAWINGS">FIG. 2C</figref> depicts the same embodiment from a front view looking at the cutting blade side of the tool, with the blade reversed to make a cut in direction <b>203</b>. The views of <figref idrefs="DRAWINGS">FIGS. 2B and 2C</figref> show that the recessed blade holding portion <b>219</b> of the blade holding face <b>221</b> is configured to accept the blade for cutting in either direction, right or left. As depicted in <figref idrefs="DRAWINGS">FIGS. 2A-2C</figref> in various embodiments the tip of hook blade <b>205</b> does not extend down to the level of the tool's bottom surface <b>229</b>.

p-0029In various embodiments the blade holding face <b>221</b> is angled away from the wall <b>280</b>. This angle—called blade angle <b>239</b>—allows the vinyl material <b>290</b> to curl up against the wall into the excess space afforded by angling the blade holding face <b>221</b> and providing the bevel face <b>225</b>. The space between the wall <b>280</b> and blade holding face <b>221</b> created by blade angle <b>239</b> is especially useful if the excess of vinyl is more than a couple of inches long since the excess vinyl often has a tendency to curl back away from the wall over the top of the tool. This space is also useful when cutting interior angles. It helps to keep the leading edge of blade holding face <b>221</b> rubbing against the wall in a tight interior bend, or scraping on the vinyl <b>290</b> that is bent up against the wall. In the embodiments depicted in the figures the recessed blade holding portion <b>219</b> is configured at the same angle as blade holding face <b>221</b>. Not all implementations are configured in this manner. In some embodiments the angle of the hook blade <b>205</b> may be more, or may be less, than the blade holding face <b>221</b>.

p-0030In the embodiment depicted in <figref idrefs="DRAWINGS">FIG. 2A</figref> the blade angle <b>239</b> is approximately 15 degrees. This is a typical angle for hook blade <b>205</b> and for blade holding face <b>221</b>. If the blade angle is too great (blade too close to horizontal), the craftsman using the tool runs the risk of scratching the wall <b>280</b> should the blade come into contact with the wall. However, if the blade angle is too small (blade too close to vertical) then the blade will cut the vinyl at too much of an angle—that is, at an angle too far from perpendicular to the surface of the vinyl which is curving up towards the wall. In a typical implementation the blade angle <b>239</b> may be anywhere within the range of 8 degrees to 30 degrees, with 15 degrees being a typical blade angle. However, in some embodiments the angle <b>239</b> for hook blade <b>205</b> and for blade holding face <b>221</b> (and blade holding portion <b>219</b>) may be any of a number of other angles, or ranges of angles, including, for example, any angle or range of angles between 0 degrees (vertical) and 60 degrees.

p-0031Angle <b>243</b>, as shown in <figref idrefs="DRAWINGS">FIG. 2A</figref>, is the angle between the blade holding face <b>221</b> (or hook blade <b>205</b>) and the bevel face <b>225</b>. For the embodiment shown in the figures angle <b>243</b> is approximately 110 degrees. Typically, angle <b>243</b> it generally within the range of 85 degrees to 130 degrees, and is larger than 90 degrees for many implementations. However, in various embodiments angle <b>243</b> between the blade holding face <b>221</b> (or hook blade <b>205</b>) and the bevel face <b>225</b> may be as much as 160 degrees or as little as 30 degrees, or any angle or range of angles between these two values.

p-0032<figref idrefs="DRAWINGS">FIGS. 2A-2C</figref> depict the various faces of the tool body to be flat, planar surfaces. In some embodiments one or more of the tool body faces may be curved or otherwise non-planar surfaces. For example, in some embodiments the bevel face <b>225</b> is not a flat surface as depicted in the figures, but rather is a gently curving surface which curves up from bottom surface <b>229</b>. In such embodiments where a relatively flat bottom surface meets a curved face (e.g., bevel face), the curved bevel face can be defined to begin at a point where the bevel angle reaches 3 degrees from horizontal (or from the plane of the bottom surface). In some embodiments the bottom surface <b>229</b> and/or the blade holding face <b>221</b> may have a gentle curve or non-planar surface as well. In various other embodiments any of the different surfaces and faces of the tool body shown to be flat in the figures may have curving or sloping surfaces. Any of the surfaces or faces of the device is said to be substantially flat along a given line segment if the radius of curvature between the two points at the end of the segment is at least ten times greater than the length of the line segment. If the majority of a surface or face is substantially flat then the surface or face is said to be substantially flat.

p-0033<figref idrefs="DRAWINGS">FIG. 3A</figref> depicts a top view of the embodiment of the tool shown in <figref idrefs="DRAWINGS">FIGS. 1-2</figref>, and <figref idrefs="DRAWINGS">FIG. 3B</figref> depicts the bottom view the same embodiment. Various embodiments of the cutting tool are configured with a top surface <b>331</b> upon which the user can rest his hand while cutting vinyl. Various embodiments of the tool come in different sizes. For each embodiment there is typically a hand grip portion on or near the top configured to comfortably fit in the hand of a craftsman. For example, <figref idrefs="DRAWINGS">FIG. 3A</figref> depicts gripping portions <b>307</b> and <b>309</b> to aid in firmly grasping the tool as it is being used to slice through the vinyl floor covering material.

p-0034<figref idrefs="DRAWINGS">FIG. 3B</figref> depicts the bottom view of the embodiment of the tool shown in <figref idrefs="DRAWINGS">FIGS. 1 and 2</figref>. The bevel face <b>325</b> can be seen in the bottom view of <figref idrefs="DRAWINGS">FIG. 3B</figref>. The bevel face <b>325</b> intersects the bottom surface <b>329</b> on its lower edge. The bevel face <b>325</b> intersects the blade holding face <b>321</b> on its upper edge. This can be seen by comparing <figref idrefs="DRAWINGS">FIG. 3A</figref> with <figref idrefs="DRAWINGS">FIG. 3B</figref>, or by viewing <figref idrefs="DRAWINGS">FIG. 2A</figref>. Moreover, in the embodiment shown the sides are beveled as well, as can be seen by portions <b>333</b>. Having a beveled side portion <b>333</b> on the leading edge of the tool—the front edge in the direction of movement—helps to smooth the vinyl down into place as the tool is moved along to make its cut. The bottom view of <figref idrefs="DRAWINGS">FIG. 3B</figref> also shows the blade <b>305</b> protruding from the recessed blade holding portion on the blade holding face.

p-0035<figref idrefs="DRAWINGS">FIGS. 4A-B</figref> depict oblique views of an embodiment of the cutting tool that has two blades. This embodiment has similarities to the embodiment of <figref idrefs="DRAWINGS">FIGS. 1-3</figref>, but differs in several key respects. The embodiment of <figref idrefs="DRAWINGS">FIG. 4</figref> is similar in that it uses a hook blade to cut the vinyl. However, rather than reversing the hook blade to change cutting directions, the embodiment of <figref idrefs="DRAWINGS">FIG. 4</figref> is equipped with a hook blade on each side, hook blade <b>405</b> and hook blade <b>406</b>. Positioning the tool as shown in <figref idrefs="DRAWINGS">FIG. 4A</figref> allows the user to make a cut to the left in direction <b>435</b>. Positioning the tool as shown in <figref idrefs="DRAWINGS">FIG. 4B</figref> allows the user to make a cut to the right in direction <b>437</b>. Since the tool depicted in <figref idrefs="DRAWINGS">FIGS. 4A-C</figref> has two cutting blades, this embodiment has two bevel faces <b>425</b> and <b>426</b>, as well as two blade holding faces <b>421</b> and <b>422</b>.

p-0036Hook blade <b>405</b> is for cutting in one direction and hook blade <b>406</b> is for cutting in the other direction. Like the embodiment depicted in <figref idrefs="DRAWINGS">FIGS. 1-3</figref>, hook blades <b>405</b> and <b>406</b> do not extend down to the level of bottom surface bottom surface <b>429</b>. This can be seen in <figref idrefs="DRAWINGS">FIG. 4C</figref> which depicts a side view of the two blade embodiment of the cutting tool looking from direction <b>435</b> shown in <figref idrefs="DRAWINGS">FIG. 4A</figref>. Another similarity to the embodiment of <figref idrefs="DRAWINGS">FIGS. 1-3</figref> is that the blade is removable so it can be conveniently replaced, or flipped around to use the other end when it becomes dull (for blades with a hook at both ends). Since the hook blades do not extend down to the floor level, the tool can be used for cutting while keeping both blades snapped into place. Alternatively, it is easy to remove one of the blades while cutting with the other to avoid the possibility of tipping the tool up during cutting and scratching the vinyl floor covering.

p-0037The cutting tool has been described herein in terms of the tool body having several different faces and surfaces. In some implementations the faces may be gently curved and the intersection between the faces may be rounded rather than being a sharp edge. It can sometimes be difficult to tell where one face ends and the other face or surface begins when the intersection bounding the two faces is curved or rounded. In such instances a plane can be drawn from both surfaces (or from the average plane of surface face if the face is curved). The intersection of the two imaginary planes is bisected back towards the tool body to find the intersection of the two faces.

p-0038The various embodiments of the cutting tool, as described herein, are drawn to a handheld tool for cutting vinyl or other flooring materials. The tool does not have a motor or source of power other than that provided by the user. Instead, the tool is pushed (or pulled) by hand, allowing the hook blade to cut through the vinyl. The body and handgrips of the vinyl cutting tool may be made from any of a number of materials known to be used in making handheld tools. These materials include various types of plastics and polymer materials, metals, wood, or any material which may be molded or machined to the proper shape, and having sufficient strength to hold the hook blade while cutting the vinyl flooring material.

p-0039For the purposes of explanation and disclosure the various embodiments have been described in terms of cutting vinyl floor covering materials. However, the tool may be used to cut any type of flexible floor covering material or flexible material of including, for example, plastic and polymer matting materials, rubber mats, flexible wall panels, linoleum sheets, or any relatively flat material flexible enough to be bent up against a wall and suitable for cutting with a hand tool that is known by those of ordinary skill in the art. Furthermore, although the tool has been described in terms of cutting a vinyl flooring material, it may be used to cut any suitable material that needs to be cut to fit on a surface against a wall or other obstruction that intersects the surface such that the material being cut bends up against the wall in a manner that facilitates cutting by the hook blade.

p-0040The Stanley model 11-961 hook blade from the Stanley Tool Company™ is depicted in the various figures of this application. Other types and brands of hook blades may be used in various embodiments. A hook blade is a blade with a concave cutting edge that may, or may not end in a sharpened tip. Various sizes and shapes of hook blades can be used with the different embodiments and implementations of the present invention. A typical sized hook blade may have a cutting edge (sharpened edge) that is no more than ½ inch long and the amount of concave is no less than 3/32 inch. However, in some embodiments having a small hook blade the cutting edge may be no more than ¼ inch long and the amount of concave is no less than 3/64 inch. In other, larger embodiments the cutting edge may be up to 2 inches long with an amount of concave of no less than ⅜ inch. Various other embodiments may use a hook blade in any dimension or range between the sizes mentioned above.

p-0041The description of the various embodiments provided above is illustrative in nature inasmuch as it is not intended to limit the invention, its application, or uses. Thus, variations that do not depart from the intents or purposes of the invention are intended to be encompassed by the various embodiments of the present invention. Such variations are not to be regarded as a departure from the intended scope of the present invention.